Numerous types of rivets are known in the art. Blind rivets are distinguished in that the force required to set the blind rivet is not applied by force-absorbing stirrups on either side of a part to be riveted, but the head and foot of the rivet are pressed together by pulling on a mandrel passing through the interior of the blind rivet, the head being held at the part and the foot pulled toward the head by means of the mandrel.
An advantage of the blind rivet can be the access to only one side of the work is required. Various “designs” have been developed for self-drilling blind rivets, but the creation of self-piercing blind rivets has not been considered since the necessary deformability of the shank does not permit exertion of a piercing force.
A disadvantage of the blind rivet can be the need for holes to be drilled or punched in the work in order to set the blind rivet. This is difficult especially when two parts are to be connected to each other, the parts not being moveable relative to each other. Production of the holes in conjunction with orientation of the parts sometimes presents difficulties, therefore, the drilling and the setting of the rivet should take place in a fixed relative position of the parts. Even in the case of the self-drilling blind rivets, this problem arises during the drilling when two parts to be connected to each other may exhibit a small gap, and upon setting of the rivet, the two parts are shifted toward each other due to the shearing stresses, quality of the riveted connection may be compromised. Another disadvantage with self-drilling blind rivets includes producing chips in the surface of the parts and other such damage.
During self-piercing riveting with a solid rivet, complete filling of the annular groove of the solid rivet by the die side sheet that is being fastened is necessary for the fastening of metal sheets. With current dies, however, this filling of the annular groove is not always completely successful. This is due to the fact that when a solid rivet is being set to the die side sheet, undesirable deformations may occur at the start of the riveting operation. Deformations can occur at the outside margin of the circular ring-shaped annular stop of the die, which is common in riveting hardware, and the displaced material, which flows into deformations, is then unavailable for filling the annular groove of the solid rivet. A disadvantage of current dies in self-piercing riveting with a solid die side sheet is the riveted connection produced in this way does not achieve a strong rivet connection. A further disadvantage can include the displaced material that flows into deformations produces ripples around the rivet joint leaving crater-like deformations around the rivet joint on a smooth surface of the die side sheet.
The teachings of the present disclosure include a rivet element and a device, a die suited to the purpose, and a process for setting said rivet element, and/or a riveted connection and an employment of said riveted connection, whereby the disadvantages described are to be overcome. Furthermore, the teachings also include a rivet element, a device and a process for setting a rivet element, for a riveted connection, and for an employment of said riveted connection.
In addition, the teachings of the present disclosure include a device and a process that ensures strength in a rivet joint using a self-piercing solid rivet and that ensures filling of the annular groove of the rivet. In addition, the teachings also include a device and a process for self-piercing riveting with a solid rivet that prevents crater-like deformations or ripples in the die side sheet and can ensure the bottom of the solid rivet and the bottom of the die side sheet are essentially in the same plane.